1. Field of the Invention
The present invention relates to an improvement in a valve-operating device with a breather system in an engine. In this invention, a breather passage is defined in a camshaft disposed in a valve-operating cam chamber and carried on an engine body in such a manner that an inlet of the breather passage opens to an outer peripheral surface of the camshaft and an outlet of the breather passage communicates with an intake system. Consequently, the gas-liquid separation, i.e., the separation of an oil and a blow-by gas from each other, is conducted in the inlet of the breather passage in the camshaft by centrifugal force, and only the blow-by gas is guided into the breather passage.
2. Description of the Related Art
Such a valve-operating device with a breather system in an engine is already known, for example, as disclosed in Japanese Utility Model Application Laid-open No. 1-148009.
In the valve-operating device with the breather system in the engine disclosed in the above Japanese Utility Model Laid-open, a camshaft-supporting structure and a structure of drawing the blow-by gas from the breather passage in the camshaft to the outside are provided independently from each other. For this reason, such valve-operating device has a disadvantage in that the entire structure is complicated, whereby it is difficult to reduce the cost.
Accordingly, it is an object of the present invention to provide a valve-operating device of the above-described type with a breather system in an engine, wherein the blow-by gas is drawn from the breather passage in the camshaft to the outside by utilizing the camshaft-supporting structure, leading to a simplified entire structure and a reduced number of parts.
In order to achieve the above object, according to a first aspect and feature of the present invention, there is provided a valve-operating device with a breather system in an engine, including a breather passage, which is defined in a camshaft disposed in a valve-operating cam chamber and carried on an engine body in such a manner that an inlet of the breather passage opens to an outer peripheral surface of the camshaft and an outlet of the breather passage communicates with an intake system. In this invention, a bearing cap is detachably secured to the engine body for supporting an outer peripheral surface of one end portion of the camshaft with a bearing interposed therebetween, the bearing cap having a breather chamber provided therein to communicate with the outlet of the breather passage, the bearing cap also being integrally formed at an outer peripheral surface thereof with a pipe-connecting portion to which a breather pipe communicating with the breather chamber and connected to the intake system is connected.
With the above structural arrangements, the bearing cap also serves as a delivery member for delivering the blow-by gas to the breather pipe; and hence, it is possible to simplify the structure and reduce the number of parts to contribute to a reduction in cost.
According to a second aspect and feature of the present invention, in addition to the first feature, the bearing is a sealed bearing including a seal member on a side facing the breather chamber.
With the above structural arrangements, the bearing can be lubricated by an oil mist within the valve-operating cam chamber, and the entering of the oil mist into the breather chamber can be prevented by the bearing.
The above and other objects, features and advantages of the invention will become apparent from the following description of the preferred embodiment taken in conjunction with the accompanying drawings.